3D Geological Mapping Research Articles

The Ventersdorp Contact Reef model in the Kloof Gold Mine as derived from 3D seismics, geological mapping and exploration borehole datasets

A model of the Ventersdorp Contact Reef (VCR) orebody at Kloof Gold Mine was derived by integrating 3D reflection seismic data with information derived from underground mine mapping and exploration drilling. The study incorporated the depth-converted prestack time migrated (PSTM) seismic cube, the mine geomodel, faults and dikes mapped in excavations, mine development infrastructure, and intersections of the VCR by surface and underground exploration drilling. The 3D seismic data provide an accurate geometric model of the VCR orebody and its offsets. The underground mapping datasets help to define minor faults and dikes that are below seismic resolution limits. The integration of the these datasets allowed (1) for better mapping of fault architectures and distributions within the lease area, (2) definition of the likely zones of difficult ground conditions around seismically imaged dikes and faults, and (3) better predictions of the number and spacing of faults that offset the VCR within minable blocks. The model is useful in mitigating both economic and safety risks of deep mining.

Virtual Geophysics Laboratory (VGL) version 1.1: Recent developments to incorporate 3D geological maps and thermal modelling using the Underworld software

One of the major impediments to the successful development of Australia's geothermal energy resources is uncertainty around the temperature distribution in the crust. Although significant in number, the coverage of temperature measurements from wells is unevenly distributed across the continent. To overcome this impediment, thermal modelling applied to 3D geological maps is a means of predicting temperature distribution between and beneath measurement points. Underworld is a parallel, 3D geodynamic modelling code which can be used to model the temperature distribution in 3D (Quenette and Moresi, 2010). Despite its scalability and the fact that it is open-source, its uptake to date has been limited by the fact that it is not easily usable by non-specialists. In particular, the process of converting 3D geological maps and physical property data to a format that can be numerically analysed in Underworld is not straightforward. As part of a NeCTAR funded project, Geoscience Australia is working with Monash University, CSIRO, and the National Computing Infrastructure (NCI) at the ANU, to develop tools to streamline the process of importing a 3D map to Underworld, running a model and exporting the results for analysis and visualisation. The project will incorporate Underworld into the Virtual Geophysics Laboratory (VGL), an environment which enables geoscientists to store, discover, retrieve and process datasets. The goals of the project are: 1. With Monash University, develop code that allows Gocad® format 3D maps to be imported to Underworld. 2. Incorporate the 3D geological maps, and Underworld, into VGL to provide an interface for both discovering and selecting 3D maps, and importing and running them in Underworld. References Quenette S., & Moresi L. 2010. Models based experimentation: numerical modelling of 3D basin scale architecture heat & fluid flow. AGU Fall Meeting Abstracts

Use of finely detailed 3D geological projection mapping on miniatures of Unzen Volcano and Hanshin-Awaji region: a proposal for a new means of education and outreach

Use of finely detailed 3D geological projection mapping on miniatures of Unzen Volcano and Hanshin-Awaji region: a proposal for a new means of education and outreach

Visualization of geologic geospatial datasets through X3D in the frame of WebGIS

3D geo spatial data have become the normal. However, to view the data, usually expert software is required, which have up to now hindered the wide spread use of 3D scenes for the display of geological data. The internet real time 3D rendering framework X3D is assessed regarding its suitability for building a geological GIS on the internet. Especially important for geological data, 3D rendering enhances the intuitive grasp of the data and enables the user to interactively explore it. It is often necessary to find a solution to distribute this data to a wide range of interested parties, experts and non-experts alike. According to the nature of 3D data, the best technique to display geo-data, the modeling of objects and unresolved issues have to be taken into consideration. The internet is the apparent tool for the public distribution and visualization of 3D data and it was found that through the open ISO-standardized format X3D it offers a multitude of possibilities. A 3D geological interactive map was created with these prerequisites to identify challenges and possibilities through this process. It was found that the use of lead to satisfactory results, that could probably not have been achieved with another technology.

2114 鉱山における3D-GeoMap生成

In order to have an efficient operation of vehicles such as trucks and excavators in the mining area, it is desirable for mining industry to have a 3D geological map (3D-GeoMap) of the working area. For the construction of the 3D-GeoMap of the working area, a land vehicle, which carries radar sensors, global positioning system receivers, and gyro sensors, acquires the spatial data of working area, and then the point cloud data is processed to generate the triangular mesh. Complex examples are used to demonstrate the effectiveness of the proposed method.

USING CLOSE RANGE PHOTOGRAMMETRY TO MEASURE THE POSITION OF INACCESSIBLE GEOLOGICAL FEATURES

In this study, the tectonic Timras doline geological maps were successfully obtained using digital close range photogrammetric techniques. This method is more reliable, faster, more accurate, and much safer. Accurate dimensions of different aspects including depth, width, slope, cracks, and various kinds of required details can be measured and used as geological inputs to obtain 3D geological maps. Furthermore, many dangerous places cannot be accurately measured by classical methods and photogrammetric methods can be safely used in these situations. Nowadays, generally, digital close range photogrammetry is applied due to cost advantages over conventional measurement techniques. First, taking photos is quite cheap and the labor costs are lower as well. In terrestrial measurement usually only two people are needed, because only the GCP have to be signalized and measured in the terrain by geodetic methods. Photogrammetric processing itself can be done by one person. The working time of the field study is also very short in comparison to other classical methods. In addition to these advantages, the 3D models which are obtained can be used for settlement planning. Furthermore, the models can provide information that enables the preservation of geological heritage and can contribute to the development of geotourism.

Using a 3D geological mapping framework to integrate AEM, gravity and magnetic modelling - San Nicolas case history

We present an example of the use of a software framework that combines 3D geological mapping and geophysical modelling. This approach would be relevant in a wide range of applications, from regional geological mapping, groundwater studies, through to mineral or geothermal prospecting. In this instance, we illustrate a typical workflow with a case study involving the San Nicolas VMS deposit and surrounding region. An initial 3D geological map, based on sparse surface geological observations, is progressively refined using AEM and potential field modelling results. At each stage, the geological map is used to capture and communicate the inferred distribution of map units. During the latter stages of interpretation, the geological map is also used to provide constraints for potential field modelling. In addition to the opportunity for direct detection of highly conductive basement-hosted sulphide mineralisation, the availability of AEM data proved crucial in the San Nicolas example in that we were able to use these data to determine the thickness of a moderately conductive transported cover unit. This significantly reduced the ambiguity of subsequent potential field interpretations.

Querying potential field inversions for signatures of chemical alteration: an example from Cobar, NSW

Major metal resources, predominantly gold and base metals, are hosted in the Cobar region, in the Central Lachlan Orogen of NSW, (Figure 1). The Predictive Mineral Discovery Cooperative Research Centre (pmd*CRC) T11 Cobar project was a two-year, one-on-one project between the pmd*CRC, NSW DPI and five mining companies in the Cobar region: CBH Resources Ltd., Cobar Management Pty Ltd., Peak Gold Mines, Triako Resources Ltd. and Tritton Resources Ltd. The aim of the Cobar project was to undertake a 3D mineral system analysis of the Cobar region, using the ?5 Questions? framework (Price and Stoker, 2002; Barnicoat, 2007): 1. What are the geodynamic and pressure-temperature histories of the system? 2. What is the architecture of the mineral system? 3. What and where are the fluid reservoirs for the mineral system? 4. What are the fluid flow drivers and pathways? 5. What are the metal (and sulphur) transport and deposition mechanisms? The answers to the ?5 Questions? of mineral systems provide the entire context of a mineral system. This context is exceedingly important, as it provides information on all of the processes that result in the formation of mineral deposits. This paper will discuss how 3D geological maps and potential field 3D inversions can be used for regional exploration targeting by querying for signatures of alteration. The volume of interest for this study is 40 km east-west, 50 km north-south and 16 km deep. The model is discretised into cubic cells of side length 250 m³. Inversions were performed using grav3d and mag3d (Li and Oldenburg, 1998a and 1996 respectively). Before inversion, an inverse model based regional-residual separation (Li and Oldenburg, 1998b) was performed. In the terms of the ?5 Questions? approach, this paper predominantly addresses question 4, although the results also addresses questions 2 and 5.

3D geological mapping and potential field modelling of West Arnhem Land, Northern Territory

A regional scale 3D geological map of the upper crustal sequence in the West Arnhem Land region, Northern Territory, was compiled from surface mapping, limited drilling information, and liberal amounts of geological inference. Modelling of the gravity and magnetic field response of this map was proposed as a means of evaluating the viability of this geological hypothesis. A relatively large number of mass density and magnetic property measurements were available to constrain the transformation of 3D geological maps into property models in preparation for potential field modelling. The presence of numerous magnetic dykes, sills, and stratigraphic horizons provided many challenges for producing geologically-realistic magnetic property models at a regional scale. Modelling of the gravity field at this scale was far more straight forward and successful. After completing various forward modelling experiments, a stochastic procedure will be used to derive a large number of geological maps by making small changes to the highly uncertain interpretive parts of the original 3D geological map. It is expected that a subset of these derived geological maps will have associated mass density models that can adequately reproduce the gravity field observations. The common characteristics of the geological models in this subset will be isolated using statistical techniques and used to refine our representation of the regional scale 3D geological features.